Little information exists about the biology of the Calamian deer (6). It is said to occur in groups usually numbering 7 to 14 individuals, although in areas where this deer is heavily hunted, much smaller groups have been reported (7). In captivity, Calamian deer have been observed to mate and give birth year round, with a gestation period of around 222 days (9). The antlers of the male deer arise from the skin covering the front of the skull and grow within a sensitive skin containing numerous blood vessels, called velvet. After providing the growing bone with oxygen and nutrients, the velvet dries and cracks when the antlers have reached their full size and the males rub it off by hitting their antlers against small trees or shrubs. This simultaneously stains the antlers with the dark sap that seeps from the tree's bark (4).